Expansible allen setscrew wrench

ABSTRACT

An expansible Allen setscrew wrench is bored centrally to receive a tapered core and is slotted at its end that enters the noncircular recess of the setscrew. A removable driving sleeve is fitted over the core and is struck to drive the wrench down on the taper to expand the slotted end of the wrench into firm engagement with a setscrew. After the setscrew is removed, the sleeve is removed and the core is struck to release the unmoved setscrew.

United States Patent [72] Inventor John D. Bihlmaier 1,415,734 5/1922 Thomas et a1. 1735 W. Haskell St.,Tulsa, Okla. 74127 2,895,361 7/1959 Coccett....,,.................. [211 App]. No. 819,633 2,233,232 2/1941 Wilkinson [22] Filed Apr. 28,1969 2,914,330 11/1959 Wheeler...................,... {45] Paemed 1971 Primary Examiner-James L. Jones, Jr.

AtlorneyYoung & Thompson [54] EXPANSIBLE ALLEN SETSCREW WRENCH 4 Claims, 7 Drawing figs.

ABSTRACT: An expanslble Allen setscrew wrench is bored [52] US. Cl.......

2 NM 13 81 b 5 2 B centrally to receive a tapered core and is slotted at its end that enters the noncircular recess of the setscrew. A removable driving sleeve is fitted over the core and is struck to drive the wrench down on the taper to expand the slotted end of the [56] Reference Cited UNITED STATES PATENTS 2/1950 Shapiro et PATENIED M1824 lsn INVENTOR. Jo/w D. [j/b/ma/er' BY Y UDg /T/mmpwn fl TTUPNEYS EXPANSIBLE ALLEN SETSCREW WRENCH The present invention relates to Allen setscrew wrenches, that is, to wrenches designed to remove setscrews having noneircular recesses therein.

Allen setscrews often become frozen in place. An ordinary wrench having a noncircular external portion complementary to the recess in the setscrew will of course have to enter the setscrew with play; and there arises the difficulty that the wrench may be stripped at its comers, because of the high torque involved and the play by which the contact area between the wrench and the set screw is considerably reduced and the pressure per unit area is correspondingly increased. Moreover, such frozen setscrews cannot readily be removed by drilling, because they have been hardened.

Accordingly, it is an object of the present invention to provide an Allen setscrew wrench which will not be subject to stripping in use.

Another object of the present invention is the provision of an Allen setscrew wrench by which great torsion can be exerted on a frozen setscrew.

' Still another object of the present invention is the provision of an Allen setscrew wrench that can readily be expanded into gripping relation with the setscrew to be removed.

It is also an object of the present invention to provide an Allen setscrew wrench which can be easily detached from the removed setscrew.

Finally,'it is an object of the present invention to provide an Allen setscrew wrench which will be relatively simple and inexpensive to manufacture, easy to operate, and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying draw ing, in which:

FIG. 1 is a perspective view of an impact driving sleeve of a wrench according to the present invention;

FIG. 2 is a perspective view of a hex wrench and tapered rod according to the present invention; I

FIG. 3 is a perspective view with parts in section, of an emplaced Allen setscrew;

FIGS. 1-3 together comprise an exploded assembly per spective view of the working parts of the present invention;

FIG. 4 shows the assembled position, with parts in section, of a wrench according to the present invention ready to set firmly in driving relationship with a frozen Allen setscrew;

FIG. 5 is a view similar to FIG. 4 but showing the wrench firmly set;

FIG. 6 is a perspective view showing the removed screw and indicating the manner of removal of the wrench from the screw; while FIG. 7 shows the removed sleeve.

Referring now to the drawing in greater detail, there is shown a wrench indicated generally at l, for the removal of an Allen setscrew 3 frozen in a part 5. Screw 3 has a noneircular recess 7 therein by which it was set in part 5; and it is desired to remove screw 3 from part 5 by the use of the same recess, without jimmying or stripping the wrench. In the drawing, recess 7 is shown as being hexagonal; however, it will be understood that it could also be of a variety of other noneircular shapes.

To the end of thus removing the screw, the wrench 1 comprises a sleeve 9 whose outer contour is noneircular and complementary to that of recess 7, in the present case hexagonal. Sleeve 9 is traversed by an axial cylindrical bore 11 and at its lower or screw-engaging end 13 is slotted as at 15, on opposite sides thereof, for expansion into gripping contact with the interior of recess 7. At its upper end 17, sleeve 9 has an end abutment shoulder 19 disposed in a plane perpendicular to the axis of the sleeve 9.

Sleeve 9 slidably surrounds a rod 21 whose length is greater than that of sleeve 9. The lower end 23 of rod 21 is belled or outwardly tapered in a smooth figure of revolution such as a cone of small included angle.' The sliding of sleeve 9 downwardly on rod 21'causes tapered end 23 to expand the slotted lower end 13 of sleeve 9.

In order to drive sleeve 9 down overrod 21, an impact driving sleeve 25 is provided, which is cylindrical and has a central bore in which the upper end of rod 21 is slidably receivable. Sleeve 25 has an upper end surface 27 disposed in a plane perpendicular to the axis of sleeve 25, and a lower end surface 29 at its other end, also disposed in a plane perpendicular to the axis of sleeve 25. This lower end surface 29 is adapted to rest flat against shoulder 19 of sleeve 9 when the parts are in assembled relation for setting the wrench, as in FIGS. 4 and 5. Although as indicated above, the length of rod 21 is substantially greater than that of sleeve 9, the combined length of sleeves 9 and 25 is substantially greater than that of rod 21.

In operation, the sleeve 9 and the rod 21 are assembled as shown in FIG. 2 and are inserted in recess 7 in setscrew 3 in the position shown in FIG. 4. The sleeve 25 is then fitted over the upper protruding end of the rod 21. The lower end surface 29 of sleeve 25 rests flat against the shoulder 19 of sleeve 9. The upper end surface 27 of sleeve'25 is then struck with a hammer as seen in FIG. 5, todrive sleeve 9 down about the tapered end 23 of rod 21 and to expand the lower slotted end 13 of sleeve 9 into tightly gripping contact with the screw 3.

Sleeve 9 can then be rotated to loosen and remove the screw 3. To this end, sleeve 9 may have an integral radially extending handle thereon (not shown); or else a socket wrench having an internal contour complementary to the external contour of sleeve 9 may be slid down over sleeve 9 and turned. It may be wondered why such a wrench would not strip or jimmy sleeve 9 if a wrench inserted in recess 7 of screw 3 would strip or jimmy. The reason is that the recess 7 in screw 3 is of necessity relatively shallow, limited as it is by the length of the screw. But the axial extent of sleeve 9 is no so limited, and an appropriately long socket wrench can accordingly be used on sleeve 9, whereby the pressure per unit area is so reduced as to avoid the danger of stripping of jimmying.

Once the set screw is removed, the sleeve 25 can be taken off and the parts have the position shown in FIG. 6. By striking the upper end of rod 21 as seen in FIG. 6, the rod 21 with its tapered end 23 can be driven axially part way out of sleeve 9, which permits lower end 13 of sleeve 9 to resume its previous smaller diameter, so that the removed set screw can simply drop or be knocked ofi the wrench. Of course the sleeve 9, and preferably also the rod 21 and the sleeve 25, are of steel and have the strength and resiliencyto undergo this operation.

In view of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved. Although the present invention has been described and illustrated in connection with a preferred embodiment, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand, Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Having described my invention I claim:

1. An Allen setscrew wrench, comprising a rod having an endwise outwardly tapered end, a first sleeve slidable on the rod and having a resiliently deformable end engageable with the tapered end of the rod so that the movement of the first sleeve on the rod toward the tapered end of the rod resiliently deforms the end of the first sleeve outwardly into contact with the side walls of a socket of an Allen setscrew, the outer contour of said end of the first sleeve being noncircular, the length of the first sleeve being substantially less than the length of the rod, and a second sleeve slidably engageable over the end of the rod opposite the tapered end of the rod and engageable with the end of the first sleeve which is opposite said resiliently deformable end of the first sleeve, the combined length of the two sleeves being greater than the length of the rod.

2. A wrench as claimed in claim 1, said first sleeve being elongated and having a uniform outer contour from end to end thereof.

3. A wrench as claimed in claim 2, said outer contour being sleeve being slotted in a direction parallel to the axis of the 4. A wrench as claimed in claim 1, said end of said first 

1. An Allen setscrew wrench, comprising a rod having an endwise outwardly tapered end, a first sleeve slidable on the rod and having a resiliently deformable end engageable with the tapered end of the rod so that the movement of the first sleeve on the rod toward the tapered end of the rod resiliently deforms the end of the first sleeve outwardly into contact with the side walls of a socket of an Allen setscrew, the outer contour of said end of the first sleeve being noncircular, the length of the first sleeve being substantially less than the length of the rod, and a second sleeve slidably engageable over the end of the rod opposite the tapered end of the rod and engageable with the end of the first sleeve which is opposite said resiliently deformable end of the first sleeve, the combined length of the two sleeves being greater than the length of the rod.
 2. A wrench as claimed in claim 1, said first sleeve being elongated and having a uniform outer contour from end to end thereof.
 3. A wrench as claimed in claim 2, said outer contour being polygonal.
 4. A wrench as claimed in claim 1, said end of said first sleeve being slotted in a direction parallel to the axis of the first sleeve. 